SUMMARYHLA‐DRB1*04 allele frequencies have been determined in 184 HLA‐DR4‐positive unrelated blood donors from the South Wales area, using group‐specific polymerase chain reaction (PCR) amplification and hybridization with sequence‐specific oligonucleotide probes, PCR amplification with sequence‐specific primers, and PCR single‐strand conformation polymorphism analysis.Eight of the fifteen known HLA‐DR4 sequences were detected in this study. Linkage disequilibrium analysis of HLA‐DRB1 *04 and HLA‐B, ‐DR and ‐DQ alleles revealed distinct haplotypic associations for all the major alleles detected in this population, including the novel linkage of HLA‐B55 with DRB1*0407.These results are relevant to the role of HLA‐DRB 1*04 haplotypes in determining allogeneic histocompatibility